/*
 Copyright  2002-2007 MySQL AB, 2008 Sun Microsystems
 All rights reserved. Use is subject to license terms.

  The MySQL Connector/J is licensed under the terms of the GPL,
  like most MySQL Connectors. There are special exceptions to the
  terms and conditions of the GPL as it is applied to this software,
  see the FLOSS License Exception available on mysql.com.

  This program is free software; you can redistribute it and/or
  modify it under the terms of the GNU General Public License as
  published by the Free Software Foundation; version 2 of the
  License.

  This program is distributed in the hope that it will be useful,  
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
  02110-1301 USA

 */

package com.mysql.jdbc.jdbc2.optional;

import java.lang.reflect.Constructor;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import javax.sql.ConnectionEvent;
import javax.sql.ConnectionEventListener;
import javax.sql.PooledConnection;

import com.mysql.jdbc.ConnectionImpl;
import com.mysql.jdbc.ExceptionInterceptor;
import com.mysql.jdbc.SQLError;
import com.mysql.jdbc.Util;

/**
 * This class is used to wrap and return a physical connection within a logical
 * handle. It also registers and notifies ConnectionEventListeners of any
 * ConnectionEvents
 * 
 * @see javax.sql.PooledConnection
 * @see org.gjt.mm.mysql.jdbc2.optional.LogicalHandle
 * @author Todd Wolff <todd.wolff_at_prodigy.net>
 */
public class MysqlPooledConnection implements PooledConnection {

	private static final Constructor JDBC_4_POOLED_CONNECTION_WRAPPER_CTOR;

	static {
		if (Util.isJdbc4()) {
			try {
				JDBC_4_POOLED_CONNECTION_WRAPPER_CTOR = Class.forName(
						"com.mysql.jdbc.jdbc2.optional.JDBC4MysqlPooledConnection")
						.getConstructor(
								new Class[] { com.mysql.jdbc.Connection.class });
			} catch (SecurityException e) {
				throw new RuntimeException(e);
			} catch (NoSuchMethodException e) {
				throw new RuntimeException(e);
			} catch (ClassNotFoundException e) {
				throw new RuntimeException(e);
			}
		} else {
			JDBC_4_POOLED_CONNECTION_WRAPPER_CTOR = null;
		}
	}

	protected static MysqlPooledConnection getInstance(com.mysql.jdbc.Connection connection) throws SQLException {
		if (!Util.isJdbc4()) {
			return new MysqlPooledConnection(connection);
		}

		return (MysqlPooledConnection) Util.handleNewInstance(
				JDBC_4_POOLED_CONNECTION_WRAPPER_CTOR, new Object[] {
						connection}, connection.getExceptionInterceptor());
	}
	
	/**
	 * The flag for an exception being thrown.
	 */
	public static final int CONNECTION_ERROR_EVENT = 1;

	/**
	 * The flag for a connection being closed.
	 */
	public static final int CONNECTION_CLOSED_EVENT = 2;

	// ~ Instance/static variables .............................................

	private Map connectionEventListeners;

	private Connection logicalHandle;

	private com.mysql.jdbc.Connection physicalConn;
	
	private ExceptionInterceptor exceptionInterceptor;

	// ~ Constructors ..........................................................

	/**
	 * Construct a new MysqlPooledConnection and set instance variables
	 * 
	 * @param connection
	 *            physical connection to db
	 */
	public MysqlPooledConnection(com.mysql.jdbc.Connection connection) {
		this.logicalHandle = null;
		this.physicalConn = connection;
		this.connectionEventListeners = new HashMap();
		this.exceptionInterceptor = this.physicalConn.getExceptionInterceptor();
	}

	/**
	 * Adds ConnectionEventListeners to a hash table to be used for notification
	 * of ConnectionEvents
	 * 
	 * @param connectioneventlistener
	 *            listener to be notified with ConnectionEvents
	 */
	public synchronized void addConnectionEventListener(
			ConnectionEventListener connectioneventlistener) {

		if (this.connectionEventListeners != null) {
			this.connectionEventListeners.put(connectioneventlistener,
					connectioneventlistener);
		}
	}

	/**
	 * Removes ConnectionEventListeners from hash table used for notification of
	 * ConnectionEvents
	 * 
	 * @param connectioneventlistener
	 *            listener to be removed
	 */
	public synchronized void removeConnectionEventListener(
			ConnectionEventListener connectioneventlistener) {

		if (this.connectionEventListeners != null) {
			this.connectionEventListeners.remove(connectioneventlistener);
		}
	}

	/**
	 * Invoked by the container. Return a logicalHandle object that wraps a
	 * physical connection.
	 * 
	 * @see java.sql.DataSource#getConnection()
	 */
	public synchronized Connection getConnection() throws SQLException {
		return getConnection(true, false);
		
	}
	
	protected synchronized Connection getConnection(boolean resetServerState, 
			boolean forXa)
		throws SQLException {
		if (this.physicalConn == null) {

			SQLException sqlException = SQLError.createSQLException(
					"Physical Connection doesn't exist", this.exceptionInterceptor);
			callConnectionEventListeners(CONNECTION_ERROR_EVENT, sqlException);

			throw sqlException;
		}

		try {

			if (this.logicalHandle != null) {
				((ConnectionWrapper) this.logicalHandle).close(false);
			}

			if (resetServerState) {
				this.physicalConn.resetServerState();
			}

			this.logicalHandle = ConnectionWrapper.getInstance(this, 
					this.physicalConn, 
					forXa);
		} catch (SQLException sqlException) {
			callConnectionEventListeners(CONNECTION_ERROR_EVENT, sqlException);

			throw sqlException;
		}

		return this.logicalHandle;
	}

	/**
	 * Invoked by the container (not the client), and should close the physical
	 * connection. This will be called if the pool is destroyed or the
	 * connectionEventListener receives a connectionErrorOccurred event.
	 * 
	 * @see java.sql.DataSource#close()
	 */
	public synchronized void close() throws SQLException {
		if (this.physicalConn != null) {
			this.physicalConn.close();
			
			this.physicalConn = null;
		}
		
		if (this.connectionEventListeners != null) {
			this.connectionEventListeners.clear();
			
			this.connectionEventListeners = null;
		}
	}

	/**
	 * Notifies all registered ConnectionEventListeners of ConnectionEvents.
	 * Instantiates a new ConnectionEvent which wraps sqlException and invokes
	 * either connectionClose or connectionErrorOccurred on listener as
	 * appropriate.
	 * 
	 * @param eventType
	 *            value indicating whether connectionClosed or
	 *            connectionErrorOccurred called
	 * @param sqlException
	 *            the exception being thrown
	 */
	protected synchronized void callConnectionEventListeners(int eventType,
			SQLException sqlException) {

		if (this.connectionEventListeners == null) {

			return;
		}

		Iterator iterator = this.connectionEventListeners.entrySet().iterator();
		
		ConnectionEvent connectionevent = new ConnectionEvent(this,
				sqlException);

		while (iterator.hasNext()) {

			ConnectionEventListener connectioneventlistener = (ConnectionEventListener) ((Map.Entry)iterator
					.next()).getValue();

			if (eventType == CONNECTION_CLOSED_EVENT) {
				connectioneventlistener.connectionClosed(connectionevent);
			} else if (eventType == CONNECTION_ERROR_EVENT) {
				connectioneventlistener
						.connectionErrorOccurred(connectionevent);
			}
		}
	}
	
	protected ExceptionInterceptor getExceptionInterceptor() {
		return this.exceptionInterceptor;
	}
}